Transformation of relaxation oscillations



p 1939. K. SCHLESINGER 2,173,500

TRANSFORMATION OF RELAXATION OSCILLATIONS Filed March 18, 1937 hue/7hr WWW Patented Sept. 19, 1939 Kurt Schlesinger, Berlin, Germany, assignor to Radioaktiengesellschaft D. S. Loewe, Berlin- Steglitz, Germany Application March 18, 1937, Serial No. 131,689 in Germany March 28, 1936 2 Claims.

' The invention relates to the production of defleeting Voltages in Braun tubes by means of a relaxation oscillation generator. Instead of to connect the storage condenser of said generator 5 directly to the deflecting plates it is advantageous to use an amplifier tube the grid of which is controlled by the generator and in the anode circuit of which feeds the primary of a stepup transformer the secondary of which is conl nested in push-pull to the deflecting plates. The relaxation device may accordingly be operated with low anode potentials of approximately 200 volts. The difiiculty associated with the method consists in the fact that, when an ordinary tri- 1 ode or pentode having a high inner resistance is used for amplification, on the transformer appears not the curve of the storage condenser potential but about its time differential curve. It has accordingly been set forth in an earlier application Ser. No. 106,021 filed Oct. 16, 1936 that the relaxation voltage curve has to be integrated by charging a second condenser from the relaxation condenser before applying it to the grid, in order to obtain the correct deflection. In this method a disadvantage consists in the fact that the two condensers must be discharged simultaneously by way of a discharge tube having two anodes. It is the object of the invention to obtain the desired result on a so simpler way which is based on the fundamental idea that on the secondary side of the transformer the correct linear relaxation curve appears if the transformer operates with a primary circuit having a very small internal resistance. The difficulty in putting this idea into practice resides in the fact that amplifying tubes, the internal resistance of which is small as compared to the primary input resistance of the transformer would require to be very large and 40 uneconomical triodes. According to the invention, there is employed a normal triode provided with a small, adjustable anode resistance.

From the point of view of the transformer the inner working resistance of the tube is then equal 5 to that of the parallel connection of tube and resistance 55, and consequently able to be reduced at desire by reducing the latter, of course with a certain loss of amplification.

The drawing shows an embodiment of the 50 method. The battery i charges the storage condenser 3 in linear fashion by way of a resistance 2. For the purpose of discharge there may be employed a simple gas-filled troide 9. A resistance H for limiting the discharge current may 55 be provided. By way of a blocking condenser I3- the relaxation voltage is applied to the grid of a triode l, which is negatively biassed by way of resistance i l, and amplified in linear fashion. The internal resistance of l, which resistance in itself is selected to be very small-tube with 5 small amplification facto-ris still further reduced in adjustable fashion by the parallel resistance I 5 according to the invention. I5 is of the order of 1,000 to 5,000 ohms. The transformer 6 is coupled to the anode circuit by Way 1 of a large blocking condenser 16. The transformer is sufiiciently well insulated between primary and secondary winding to prevent the high anode potential of the Braun tube from passing to earth. It is even possible by adjustment of 15 the resistance E5 to convert a convex-distorted deflection curve into a concave distorted one, and accordingly to obtain a linear one.

The transformer 6 must be capable of sufficiently transmitting the lowest frequency, i. e., 20 the relaxation frequency itself and some harmonies of it. For the image-change figure there may be employed a transformer which transmits between 50 and 3,000 periods; for the line change there is requested, corresponding to the number 26 of lines, a higher frequency band, for example in the case of a ZOO-line image a band of between L500 cycles and approximately 100 kilocycles.

In order to impose the relative smallness of 30 the inner resistance the impedance of the primary winding of 6 should be made as large as possible. There should accordingly be provided as many turns as possible on the transformer. This is simplified by the fact that, in accordance 5 with the invention, the direct current is blocked by the capacitative coupling IS. The Wire, therefore of the secondary primary winding may be reduced in thickness to the smallest technical degree, i. e., in practice to approximately 0.01-0.07 mm.

Practical embodiment:

Transformation ratio: 1:6,

Number of primary turns 4,500,

Amplifier factor of triode 7:10,

Internal resistance of 7=approximately 5,000

ohms,

Anode resistance 15:3,000 ohms,

Anode current approximately 10 milliamperes,

Voltage of battery 1:300 volts,

Transformation ratio of the potentials accomplished in practice approximately 1:4,

Potential between the plates approximately 700 volts.

I claim:

1. In an arrangement for the production of the deflecting voltages in a cathode ray tube having a pair of deflecting plates comprising a relaxation oscillation generator, an amplifying tube the grid of which is controlled by said generator and a step-up transformer the primary of which is connected to the output of said amplifying tube and the secondary of which is connected to the deflecting plates of the cathode ray tube, an adjustable resistance shunting the primary of said transformer, said resistance being small as compared to the reactance of said primary.

2. In an arrangement for the production of the deflecting voltages in a cathode ray tube having a pair of deflecting plates comprising a relaxation oscillation generator, an amplifying tube the grid of which is controlled by said generator, and a large step-up transformer the primary of which is connected to the output of said amplifying tube and the secondary of which is connected to the deflecting plates of the cathode ray tube, an adjustable resistance shunting the primary of said transformer, said resistance being small as compared to the reactance of said primary, said amplifying tube being a triode of small amplification factor.

KURT SCI-ILESINGER. 

